Reducted Movement - How do you do 1/10 rates?

[jodyjohnson]

How do you handle movement for such spells as Solid Fog which reduce movement rates to 10%? 2' or 3' per move seems touch to measure on the 5' grid.

What would be the movement rate for Medium armored (20') in snow (1/2) in a Solid Fog (1/10)? (Likely while fighting say a White Dragon).

Do 5' adjustments ever get reduced by terrain/movement reductions?

 

[MarauderX]

I think 5' is the minimum unless encumbered. Could be wrong, but I think there is something about running in the dark, while blind, etc. that calls for a reflex save per round to stay standing or avoid something dangerous (cliff, pit, wall). Don't have my books in front of me, though someone should help out soon.